Dental endosseous root implant

ABSTRACT

The invention relates to a dental endosseous root implant with a first part to be completely embedded in and covered over in a tooth socket and a second part carrying a crown or other prosthetic device. The first part has a root portion or dowelreceiving socket on a crown base or platform with an integral surrounding tapered latticed body freely fitting in the tooth socket or prepared bone socket through which bone tissue may grow to embed and secure the dowel-receiving socket in the alveolar process. The second part has a dowel fitting the socket and carries a crown or the like. The implant technique involves selection of a properly sized root implant or dowel-receiving socket to fit freely but snugly into the tooth socket anytime after extraction of the tooth being especially applicable immediately after extraction of the tooth. The gingival tissue over the root implant is then approximated and sutured together. A blood clot fills the socket around the endosseous root implant and is gradually replaced by a fibrous meshwork. The final stage of healing results in continued deposition of bone around and through the latticed body. During the entire period of healing the root implant is under no occlusal or biting stress nor disturbed by the bacterial flora or oral debris since it was completely embedded in the socket and covered over by oral mucosal tissue. The bone tissue embeds the device and the sealed socket is then exposed only at the top of the root implant whereupon the second or more parts including a dowel crown is firmly attached to the root implant.

United States Patent [72] Inventors Sidney D. Gault 810 D Skokie l-lwy,Wilmette, 111. 60091; Gerald M. Silverman, 4250 Marine Drive,

Chicago, 111. 60613 [21 Appl. No. 744,739 [22] Filed July 15, 1968 [45]Patented Apr. 27, 1971 [54] DENTAL ENDOSSEOUS ROOT IMPLANT PrimaryExaminer-Robert Peshock Attorney-W. Lee Helms, Esq.

ABSTRACT: The invention relates to a dental endosseous root implant witha first part to be completely embedded in and covered over in a toothsocket .and a second part carrying a crown or other prosthetic device.The first part has a root portion or dowel-receiving socket on a crownbase or platform with an integral surrounding tapered latticed bodyfreely fitting in the tooth socket or prepared bone socket through whichbone tissue may grow to embed and secure the dowelreceiving socket inthe alveolar process. The second part has a dowel fitting the socket andcarries a crown or the like. The implant technique involves selection ofa properly sized root implant or dowel-receiving socket to fit freelybut snugly into the tooth socket anytime after extraction of the toothbeing especially applicable immediately after extraction of the tooth.The gingival tissue over the root implant is then approximated andsutured together. A blood clot fills the socket around the endosseousroot implant and is gradually replaced by a fibrous meshwork. The finalstage of healing results in continued deposition of bone around andthrough the latticed body. During the entire period of healing the rootimplant is under no occlusal or biting stress nor disturbed by thebacterial flora or oral debris since it was completely embedded in thesocket and covered over by oral mucosa! tissue. The bone tissue embedsthe device and the sealed socket is then exposed only at the top of theroot implant whereupon the second or more parts including a dowel crownis firmly attached to the root implant.

PATENTEDAPRNIQH 3576p,

sum 2 0F 3 llllll"lll INVENTORS .fi/o/ver O. 644/11 Gee/:40 M.SILVERMA/V I I w 2 a, ATTORNEYS B W x TENT/kl. ENSSEOUS BOUT IMPLANTlFlELD OF THE INVENTION This invention relates to a dental endosseousroot implant consisting of a root portion or dowel-receiving socketcompletely embedded within bone tissue for 6-8 weeks or untilroentgenographic evidence of bone formation and then exposed occlusallyto receive dowel-pin crown or other dental prosthetic device.

PRIOR ART Heretofore known dental implant devices have involved thepresence of occlusal or biting stress on the implant during the earlystages of bone formation thus delaying and even preventing formation ofa bone anchor for the implant. When an occlusal or biting force wasapplied to an implant, there was tendency toward displacement of theroot portion into the alveolar base or rotation or tilting of theimplant resulting in bone destruction, therefore diminishing thepossibilities of firm and lasting attachment of the bone to the implant.Generally, much skill and experience was required by the operator, thepatient was involved in long dental procedures, the implant frequentlyhad to ligated or splinted to adjacent teeth and often required thecutting of the bone to shape the socket or forcibly threading animplantscrew into the bone resulting in trauma of the alveolar process.

SUMMARY According to this invention, there is provided a two or morepart dental implant with a root portion or dowel-receiving socketdeposited in the tooth socket anytime after extraction of the toothbeing especially applicable immediately after extraction of the toothand sized to freely but snugly fit in the socket. The second partcarries the crown or other dental prosthetic device and is affixed tothe first part only after the first part has become embedded in thetooth socket by adequate fiber or bone deposition. The two parts arecomposed of relatively inert materials such as metals which areelectropassive particularly Vitallium," tantalum, 1M SMO steel andtitanium or any other suitable metal or synthetic resins such as methylmethacrylate, polyethylene, polyvinyl alcohol (lvalon),polytetrafluoroethylene (Teflon), and plasticceramics or any othersuitable synthetic resin. In some cases, it may be desirable to coat theroot portion with a porous material such as a ceramic-plastic, plasticepoxy resin or any other suitable material which allows fibrousconnective tissue, dense collagen fibers and perhaps bone to invade theopen pore structure analogous to the periodontal membrane attachment ofteeth to bone.

The preferred first part or root implant unit of this invention iscomposed of a central elongated open-topped, closed-bottom tube in thecenter of an open cage or basket composed of a plurality of rings spacedalong the length of the tube and decreasing in diameter from the opentop to the closed bottom of the tube. These rings are supported from thetube on radially extending struts. A U-shaped bight extends from the topring and under the bottom of the tube with its side legs secured to therings and its bight portion spaced beyond the closed bottom of the tube.The top ring and struts are flush with the open top of the tube andprovide a platform adopted to be exposed in the tooth socket forreceiving the crown base or any other dental prosthetic device of thesecond part. This second part has a base mating with the platform of thefirst part or any other form of attachment and a depending dowel pinfitting the tube. The second part also has a dental prepared crown onthe base over which the anatomical crown or any other dental prostheticdevice is fitted. The anatomical crown is firmly attached, preferablycemented or mechanically attached to the dental prepared crown and thepin or dowel and crown base are firmly attached to the first pan, theroot implant. The open cage or basket of the first pan thus surroundsthe tube or dowel-pin socket in spaced concentric relation and providesan open lattice work through which bone tissue will readily grow so thatthe bight of the cage will be firmly embedded in bone. The latticeforming the cage allows the blood clot to fill the socket around theendosseous root implant resulting in a fibrous meshwork and finallydeposition of bone. The shape and size of the cage may be varied asdesired to fit the particular tooth socket. The implant unit can befurnished in kits containing a wide selection of shapes and sizes sothat the dentist will have a free choice of selecting the implant partmost suitable for the socket involved. This socket. is preferably thenatural tooth socket immediately following extraction of the tooth, buta prepared bone socket is also applicable.

The root implant part is preferably cast, molded or produced in onepiece and while the invention will hereinafter be specifically describedas embodied in an implant for a single rooted tooth, it is'to beunderstood that the implant part can be furnished as a multirooteddevice, connected by a strut or other bridge for insertion into thesocket of a multirooted tooth. The multirooted implant parts will thenprovide platforms on which the crown base or any other dental prostheticdevice will rest and this crown base can have a plurality of dowel pinsinserted into the pin sockets of the implant parts.

If desired, a cushioning of the crown base or any other dentalprosthetic device on the root implant can be provided by interposing aresilient material, spring, air cushion or any other suitable devicebetween the base and the top of the implant and/or between the base ofthe tube socket and apex or end of the dowel pin.

The principle object of the invention is to provide a simple firmendosseous root implant device for attaching crowns, copings,bridgework, full and partial dentures and any other dental prostheticdevice. I

Another object of this invention is to provide a dental implant with anintegral surrounding tapered latticed body freely fitting in the toothsocket or prepared bone socket through which bone tissue may grow, embedand secure the root implant in the alveolar process.

Another object of this invention is to provide an endosseous implantwhich is under no occlusal or biting stress nor disturbed by thebacterial flora or oral debris during bone deposition andimmobilization.

An important object of this invention is to provide a dental implanthaving a central dowel-pin receiving socket or root implant surroundedby an open latticed body adapted to be freely but snugly sealed in atooth socket anytime after extraction of the tooth, being especiallyapplicable immediately after extraction of the tooth therefrom toreceive bone tissue therethrough and therearound to provide a fixedanchor in the tooth socket together with a second part carrying a crownor any other dental prosthetic device and a dependent dowel pin fittingthe dowel-pin socket for fixed attachment to the root implant.

A specific object of this invention is to provide a dental endosseousimplant having a first part with a central elongated closed-bottom,open-topped tube surrounded by an open lattice basket connected to thetube through struts together with a second part for carrying a dowelcrown or having a dowel crown base or any other dental prosthetic deviceto be secured to the top of the first part and a dowel pin extendingfrom the base to be secured in the tube of the first part.

Another object of this invention is to provide a device for anchoringcrowns in a human mouth which involves depositing a free-fitting rootimplant in the tooth socket anytime after extraction of a tooth beingespecially applicable immediately after extraction of the tooth followedby the sealing of the socket as by the use of sutures or any otherdevice closing the wound over the top of the implant until bone tissuesubstantially filled the tooth socket and firmly embedded the implant.

Another object of this invention is to provide a two-part crown anchor,including an implant part with a pin-receiving socket and a crown basepart with a pin fitting the socket.

Other and further objects of this invention will become apparent tothose skilled in this art from the following detailed description of theannexed sheets of drawings which, by way of preferred examples only,illustrate several embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a generally perspective viewof the two components of the crown anchor according to this invention.

FIG. 2 is a longitudinal cross-sectional view along the line llII ofFIG. 1. I

FIG. 3 is a transverse cross-sectional view along the line IIIIII ofFIG. 1.

FIG. 4 is a somewhat schematic view of several teeth and teeth socketsin a human jaw illustrating a tooth to be extracted.

FIG. 5 is a view similar to FIG. 4 but illustrating the extrac tion siteor tooth socket after the extraction.

FIG. 6 is a view similar to FIG. 5 but illustrating the implant deviceof this invention inserted in the extraction site or empty tooth socketof FIG. 5.

FIG. 7 is a view similar to FIG. 6 but illustrating the closing of thetooth socket for the healing process.

FIG. 8 is a view similar to FIG. 7 but illustrating the embedded implantdevice after completion of the healing process and deposition of bonearound implant root and also showing the uncovered top of the implantreceiving the dowel crown and anatomical crown.

FIG. 9 is a somewhat schematic view illustrating a multirooted implantdevice according to this invention positioned in a multirooted toothsocket.

FIG. 10 is a greatly enlarged section taken along the line X-X of FIG. 8illustrating the fibrous connective tissue, dense collagen fibers orperhaps bone fibers approximating the implant device in the alveolarprocess of the jaw bone.

FIG. 11 is a view similar to FIG. 10 but illustrating the fibrousconnective tissue, dense collagen fibers or perhaps bone fibers invadingthe open pore structure of a porous coating around the root portion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The dowel-crown-root endosseousimplant 10 of this invention, as illustrated in FIGS. 1 and 2, includesa root implant component 11 and a crown carrier component 12. The rootimplant component 11 is unitary and is composed of a central elongatedtube 13 with a closed bottom 14 and an open top 15. The tube ispreferably tapered and provides a tapered pin socket 16. The tube 13 issurrounded by a cage or basket 17 composed of three axially spaced ringsI8, 19 and 26 decreasing in diameter and joined to the tube 13 by radialstruts or ribs 21, four equally spaced struts 21 being illustrated foreach ring. A longitudinally extending U-shaped strut 22 envelopes thethree rings 18, 19 and and is integrally affixed to the peripheries ofthese rings. The bight portion 224 of this strut 22 is spaced below theclosed end 14 of the tube 13. Since the rings 18, 19 and 20 are ofdecreasing diameter, the U-shaped strut 22 converges from the top ring18 to the bight 22a and a tapered contour is thereby provided for thecomponent 11.

The top ring 18 cooperates with the radial struts 21 and the rim of theopen-topped tube 13 to provide a flat top platform 23 for the component11. The top platform 23 is surrounded by a cylindrical wall 230 affordedby the periphery of the top ring 18.

The component 12 has a circular crown base 24 with a recessed bottom 25surrounded by a cylindrical peripheral skirt or shoulder 25a. A taperedpin or dowel 26 depends from the central portion of the crown base 24and a prepared crown 27 extends upwardly from the top of the base 24.The recess 25 is adapted to receive the top platform 23 therein with theskirt 25a snugly embracing the cylindrical wall 230 of the unit 11. Thepin 26 fits the socket 16'of the central tube 13 and as hereinafter morefully explained, the base 24 is cemented or mechanically attached to theplatform 23 and the pin 26 is cemented or mechanically attached in thesocket 16.

As shown in FIG. 3, there is considerable space or gap between the tube13 and the surrounding rings such as 19 and struts 22. The unit 11 thushas an open latticelike cage surrounding the central tube 13.

As shown in FIG. 4, three teeth 28, 29 and 30 are illustrated with theirroots extending into sockets provided by the honey tissue of thealveolar process 31 of a human jaw. The tooth sockets illustrated at 32,33 and 34 are lined with a periodontal membrane 35 and the roots of theteeth are connected by fibers through this membrane to the alveolarprocess. The center tooth 29 is illustrated as very carious at 34indicating that the tooth is beyond repair and indicated for extraction.

Upon removal of the tooth 29, as illustrated in FIG, 5, there remains anextraction site or socket 36 with a closed bottom and an open top andwith remnants of the periodontal membrane 35 remaining in the emptysocket, portions of the membrane adhering to the extracted tooth andother portions adhering to the alveolar process 31.

In accordance with this invention and as shown in FIG. 6, the extractionsite or hollow socket 36 receives the implant unit 11 anytime afterextraction of tooth 29, being especially applicable immediately afterextraction of the tooth 29. An implant unit 11 of proper size isselected to freely but snugly fit the socket 36 without requiringdrilling of the bone for the preferable immediate implant or water-coolbur preparation of the bone for the delayed implant so that implantingof the unit will not create unnecessary trauma. It will be understood,however, that the selected implant unit 11 will be so dimensioned andshaped as to closely approximate the tooth socket thereby avoidingappreciable socket preparation. In other words, the implant 11 isselected to fit the unaltered socket freely but snugly wherever possibleto eliminate trauma. As shown, the top platform 23 is somewhat depressedunder the opening 36a of the socket so that surrounding gingival tissuemay be drawn over the platform as illustrated in FIG. 7, wherein sutures37 close the top of the extraction site or wound to completely incasethe unit 11 within the socket 36.

After unit 11 is implanted and the top of the extraction site or woundis sutured incasing the unit 11 within the socket 36, a blood clot fillsthe socket 36 around the endosseous root implant and finally depositionof bone completely embeds and interlocks the unit 11 as shown in FIG. 8.As therein shown, the bone 31a is continuous with the surrounding bone31 and is integral therewith.

During a period of about 68 weeks or until roentgenographic evidence ofbone formation, the root implant unit 11 is under no occlusal or bitingstress nor disturbed by the bacterial flora or oral debris since unit 11is completely embedded in the socket and completely covered over by oralmucosa] tissue. Therefore, during the entire healing process, theimplant is not exposed to the harmful influences of the externalenvironment.

Upon roentgenographic evidence of sufficient bone growth to provide thefixed anchor for the implant in the tooth socket, the top of the socketis opened up to expose the platform 23 as illustrated in FIG. 8 and theprepared dowel-crown unit 12 is mounted on the platform 23 with thecrown base being temporarily cemented or mechanically attached to theplatform 23 and with the dowel pin 26 being temporarily cemented ormechanically attached in the tube 13. Thus, for the first time unit 11is exposed and subject to the external occlusal or biting stress,bacterial flora and oral debris only after deposition of bone resultingin an establishment of an immobilized anchor for unit 12.

Component 12 may be tested in the oral cavity in its proper position inunit 11 for a few days, after which an impression of the component 12 asit relates to the adjacent and opposing teeth may be taken. Models ofthe upper and lower teeth are made from the impression and sent to thelaboratory for production of the anatomical crown or any other dentalprosthetic device 38 to fit prepared crown 27 on component 12. Finalfinishing and polishing of anatomical crown 38 on prepared crown 27 canbe done out of the patients mouth thus saving patient-chair time,eliminating trauma, and

enabling the dentist to improve the fit of the crown. Since the preparedcrown 27 may be produced in identical measurements for most teeth, theanatomical crown 38 may be standardized in size and production by thedental laboratories.

As illustrated in H0. 9, if the natural tooth socket has a multirootedsocket 39 as when a molar tooth such as 30, is extracted, a multipleimplant device 40 may be used composed of two units -ll having their topplatforms connected by a bridge 41 spanning the socket opening 42between the two root sockets 39. The bridge connection 41 is rigid, butcan be bent under force so that the units 11 will extend at the properangles into the root sockets 39. This multirooted device is particularly applicable to upper or maxillary molar teeth immediately afterextraction of the tooth whereas an enlarged version of the previouslydescribed singleJooted tooth implant may be used for lower or mandibularmolar teeth, after removal of interradicular bone, either for theimmediate or delayed implant or for the maxillary molar delayed implant.

A crown unit 44 for the multirooted implant assembly 40 is provided witha crown base 45 having a recess 46 large enough to receive both topplatforms 23 of the units 11. The crown base 45 has dowel pins 47depending therefrom into the tubes 13 of the units 11 and has a singleprepared crown 48 receiving the anatomical crown 49 or any other dentalprosthetic device. If desired, a cushion 50, produced by interposing aresilient material, spring, air cushion or any other suitable device canbe interposed between the platforms 23 and the crown base 45 and/orbetween closed bottom of tube 13 and apex or end of dowel pins 47. Asimilar cushion, of course, could be used for the single socket implant.

As illustrated in the greatly enlarged fragmentary view of FIG. theimplant device 11 has the strut 22 provided with usually a roughenedsurface 51. This is illustrative of the entire cage surfaces includingthe rings and also the external surface of the tube 13.

The alveolar process 31 forming the socket in which the implant devicell is placed has remnants of the periodontal membrane 35 which containspluripotential cells capable of producing osteoblasts and fibroblasts.These osteoblasts and fibroblasts produce fibers 52 which approximatethe roughened surface 51 of the implant strut 22 thus forming a fibrousmeshwork 53 in the periodontal membrane space 54 which may aid inretention of the implant. The periodontal membrane space 54 averagesbetween 0.2 and 0.5 mm. This fibrous meshwork 53 grows all around theimplant device.

As shown in FIG. 11, the strut 22 of the implant device 1] may be coatedwith a porous material 55. This covering 55 is provided on all surfacesof the cage portion of the implant device 11 as well as on the externalsurface of the dowel-pin socket 13 of the device. As illustrated in FIG.11, the fibers 52 described in FIG. 10 invade the interstices or pores56 of the coating 55 and thereby enhancing; the retention of theimplant.

From the above description, it will therefore be understood that thisinvention provides a novel process for establishing the immobilizationof a dental implant by incasing the root part within a tooth socket,suturing the socket closed and allowing for deposition of bone aroundand through the latticed body. Therefore, during the entire: healingprocess, the implant is not exposed to the harmful influences of theexternal environment. Upon completion of healing, the top of the rootpart is exposed and a dowel crown as described here or any other dentalprosthetic device is attached to the root part. Therefore, thisinvention embodies a two or more part dental endosseous implant with theroot part firmly embedded and immobilized with the bone before placementof the crown or other dental prosthetic device.

Although we have herein set forth our invention embodying certainspecific structures, design and principles and details thereof, it willbe understood that various modifications and changes in the specificstructures and design may be made without departing from the basicprinciple, spirit and scope of the invention as set forth in thehereunto appended claims.

We claim:

I. A dental crown-anchoring device which includes an implant part havinga central tubular dowel socket connected in spaced relation to an openlattice cage adapted to be freely but snugly inserted and imbedded in atooth extraction site, said cage consisting of a top member centrallyapertured in communication with the tubular dowel socket, and twolaterally spaced struts forming a loop member having its strut lengthsdepending from the upper area of said tubular dowel socket, said loopmember extending longitudinally of the dowel socket and outwardly spacedtherefrom, and spaced connecting and reinforcing means projectedinwardly from the strut lengths of said loop member across the spacebetween them and the tubular dowel socket and connecting said strutlengths and said tubular dowel socket.

1. A dental crown-anchoring device which includes an implant part havinga central tubular dowel socket connected in spaced relation to an openlattice cage adapted to be freely but snugly inserted and imbedded in atooth extraction site, said cage consisting of a top member centrallyapertured in communication with the tubular dowel socket, and twolaterally spaced struts forming a loop member having its strut lengthsdepending from the upper area of said tubular dowel socket, said loopmember extending longitudinally of the dowel socket and outwardly spacedtherefrom, and spaced connecting and reinforcing means projectedinwardly from the strut lengths of said loop member across the spacebetween them and the tubular dowel socket and connecting said strutlengths and said tubular dowel socket.